Tripod joints are used, for example, as side shafts of motor vehicles. In this case, the tripod joints are used for transmitting driving torques between two driving elements of a drive train. The tripod joints permit a relative displacement and a relative pivoting of the driving elements to be compensated for. For the use in the case of side shafts of a motor vehicle, relative movements of this type are caused by spring deflections of the vehicle wheels.
U.S. Pat. No. 4,619,628 describes a tripod joint having a joint outer part and a joint inner part held in the latter. The joint inner part has a tripod star having pins having ball bodies. The ball bodies are accommodated pivotably in a recess of a pressure element. The pressure element is mounted moveably with respect to mating surfaces of the joint outer part via rolling bearings.
In the case of this conventional arrangement, pivoting of the joint inner part results in a movement of the pins and of the pressure element on a circular path. This changes the distance of the pressure element from the longitudinal axis of the joint outer part. The rolling bodies are guided in rectilinear guide grooves in the joint outer part. The different boundary conditions of the rolling bodies on the pressure element, on the one hand (circular path), and on the joint outer part, on the other hand (rectilinear movement), have to be compensated for by a sliding movement of the rolling bodies with respect to the pressure element in the longitudinal direction of the rolling bodies, which causes increased amounts of sliding. As a result, during three-dimensional movements of the tripod joint, mechanical impairments of the transmission function may occur, which, in the worst case, may result in the drive train being caused to vibrate and/or to produce noise and in resultant impairments of comfort. Furthermore, the rolling bodies having associated cages are guided in grooves of the joint outer part, which grooves require an increased outlay on manufacture for the production of the joint outer part.
German Published Patent Application No. 38 16 646 describes a tripod joint without guide grooves in the joint outer part. In this joint, however, the rolling contact is made with rolling bodies revolving around the ball body, which causes an increased outlay on construction. This type of construction also has the disadvantage of requiring play kinematically in the joint in the circumferential direction as a consequence of the revolving rolling bodies. This play may be perceptible as an impact during changes of load. Moreover, the tripod joint is expensive because of the multiplicity and complexity of the structural elements.
It is an object of the present invention to provide a tripod joint which is improved with regard to the outlay on components and manufacturing and/or to the mechanical transmission behavior.